<template>
  <view>
    <my-search @click="gotoSearch()"></my-search>
    <view class="scroll-view-container">
      <!-- 左侧滚动视图区域 -->
      <scroll-view class="left-scroll-view" scorll-y :style="{height: windowHeight + 'px'}">
        <block v-for="(item ,i) in cateList" :key="i">
          <view :class="['left-scroll-item', i === active ? 'active' : '']" @click="activeChanged(i)">
            {{item.cat_name}}
          </view>
        </block>

      </scroll-view>

      <!-- 右侧滚动视图区域 -->
      <scroll-view class="right-scroll-view" scorll-y="true" :style="{height: windowHeight + 'px'}" :scroll-top="scrollTop">
        <block class="cate-level2" v-for="(item2, i2) in cateLevel2" :key="i2">
          <!-- 二级菜单 -->
          <view class="cate-level2-title">
            {{item2.cat_name}}
          </view>
          <!-- 三级菜单 -->
          <view class="cate-level3-list">
            <view class="cate-level3-item" v-for="(item3 ,i3) in item2.children" :key="i3" @click="gotoGoodsList(item3)">
              <image :src="item3.cat_icon.replace('dev','web')"></image>
              <text>{{item3.cat_name}}</text>
            </view>
          </view>
        </block>

      </scroll-view>
    </view>
  </view>
</template>

<script>
  import badgeMix from '@/mixins/tabbar-badge.js' // 购物车数字徽标显示
  export default {
    mixins: [badgeMix],
    data() {
      return {
        windowHeight: 0,
        cateList: [],
        active: 0, // 默认第一个被选中
        cateLevel2: [],
        scrollTop: 0 // 设置切换菜单时滚动条自动回零
      }
    },
    methods: {
      // 获取分类信息
      async getCateList() {
        const {
          data: res
        } = await uni.$http.get("/api/public/v1/categories");
        if (res.meta.status !== 200) return uni.$showMsg();
        this.cateList = res.message; // 左侧大菜单
        this.cateLevel2 = res.message[0].children; // 右侧二级菜单
      },
      // 改变选中项样式
      activeChanged(i) {
        this.active = i;
        this.cateLevel2 = this.cateList[i].children; // 一级菜单改变后，为二级菜单重新赋值
        // 让滚动条随着左侧菜单的选择滚动
        this.scrollTop = this.scrollTop === 0 ? 1 : 0;
      },
      // 跳转商品页面
      gotoGoodsList(item3){
        uni.navigateTo({
          url: '/subpkg/goods_list/goods_list?cid=' + item3.cat_id
        })
      },
      // 跳转搜索页面
      gotoSearch(){
        uni.navigateTo({
          url: '/subpkg/search/search'
        })
      }
    },
    onLoad() {
      // 获取系统信息，再传递高度给windowHeight
      const sysInfo = uni.getSystemInfoSync();
      this.windowHeight = sysInfo.windowHeight - 50; // 减去搜索框，tabbar，navigationbar

      this.getCateList();
    }
  }
</script>

<style lang="scss">
  .scroll-view-container {
    display: flex;

    .left-scroll-view {
      width: 120px;

      .left-scroll-item {
        line-height: 60px;
        background-color: #f7f7f7;
        text-align: center;
        font-size: 12px;

        // 默认左侧点击项的样式
        &.active {
          background-color: #fff;
          position: relative;

          // 给点击项左侧添加一个左红色框线
          &::before {
            content: ' ';
            display: block;
            width: 3px;
            height: 30px;
            background-color: #c00000;
            position: absolute;
            left: 0;
            top: 50%;
            transform: translateY(-50%);
          }
        }
      }
    }
  }
  
  .cate-level2-title {
      font-size: 12px;
      font-weight: bold;
      text-align: center;
      padding: 15px 0;
    }
  
  .cate-level3-list {
      display: flex;
      flex-wrap: wrap;
  
      .cate-level3-item {
        width: 33.33%;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        margin-bottom: 10px;
  
        image {
          width: 60px;
          height: 60px;
        }
  
        text {
          font-size: 12px;
        }
      }
    }
  
</style>